XMP / Ram OC interfering with 1080 Ti POST???

[CalvinHobbesN7]

Alright, this is a real headscratcher. I could really use an expert on this one.

If you read my previous post, you'll know that I was having a very difficult time overclocking my RAM, both via XMP and by manually entering the DRAM timing, voltage and frequency settings. No matter what, my system would not OC the DDR4-3200 RAM past 2533. It failed POST every time.

Some System Information:

• MB: Asus STRIX Z370-E

• CPU: Intel i7-8700K

• GPU: EVGA 1080 Ti FTW3 w/ 200mm Thermaltake Riser (more on that below)

• RAM: F4-3200C16Q-32GTZSW (Listed on the MB QVL)

It turns out that RAM wasn't failing the POST test, it was the GPU. I have four POST lights for CPU, DRAM, VGA, and BOOT. The VGA light remained illuminated and would not turn off. According to the manual, that means it hasn't completed the test for that portion yet. I removed my EVGA GTX 1080 Ti FTW3 from the mix, applied the XMP for my 3200MHz RAM, and - to my shock and awe - it booted right up without a hitch. In fact it's currently running right now.

I re-connected my 1080 Ti, and it failed POST.

I reset the MB DRAM memory settings to their defaults, and it booted right up - 1080 Ti and all.

 

NOW - BEFORE YOU TELL ME MY GPU IS BROKEN:

 

You should know that this 1080 Ti has been performing remarkably under "normal" un-overclocked (and slight OC) RAM speeds between 2133 and 2533. My highest OC score in SuperPosition Benchmark with this same card via the baseline MB BIOS config is 23586.

 

Now the real question: Why on earth is overclocking the RAM causing the GPU to fail during POST testing?

 

The only possible explanation I can think of in my relatively little experience is that I'm using a shitty PCIe Riser cable. I currently have one in the mail to arrive on Saturday. But this... seems a little unlikely to me.

If YOU know what's going on, then PLEASE. TELL THE WORLD. But most importantly, tell me below because this mystery seems unsolvable.

[Srnewbee]

hmmmm... just a hunch but did you adjust BLCK when overclocking your ram? If you adjusted your BLCK then your PCIE would have been affected. As such, your GFX would fail to post.

[CalvinHobbesN7]

7 hours ago, Srnewbee said:

hmmmm... just a hunch but did you adjust BLCK when overclocking your ram? If you adjusted your BLCK then your PCIE would have been affected. As such, your GFX would fail to post.

What is BLCK? I never intentionally altered/set this, I'm unsure if XMP did though - and I experience this problem with both manual DRAM changes and XMP profile application.

[Srnewbee]

Did you overclock your CPU? If so, how did you do it? Did you only increase the multipliers? BLCK x multiplier is your clock speed. e.g. 100 BLCK x 49 multiplier would equal 4.9ghz. Sometimes, people would set their BLCK to 120 and set multipliers to 41 to achieve 4.9ghhz . If BLCK is above 100, then most components on your motherboard is overclocked. So if you overclocked your BLCK then your GPU would automatically be overclocked on top of your MSI settings.

[CalvinHobbesN7]

1 hour ago, Srnewbee said:

Did you overclock your CPU? If so, how did you do it? Did you only increase the multipliers? BLCK x multiplier is your clock speed. e.g. 100 BLCK x 49 multiplier would equal 4.9ghz. Sometimes, people would set their BLCK to 120 and set multipliers to 41 to achieve 4.9ghhz . If BLCK is above 100, then most components on your motherboard is overclocked. So if you overclocked your BLCK then your GPU would automatically be overclocked on top of your MSI settings.

I just hit the 5GHz Profile button, OR I've also simply changed to sync all cores to the 1-core limit ratio of 50.

[Srnewbee]

hmm so its not the CPU. Thats ruled out now. How about your PSU? It seems that if you take out your GFX, then your ram works and your ram does not work with the GFX. I am now suspicious of your PSU.